# Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class Sequencer::Units < SimpleDelegator

  # Initializes the lifespan store for the attributes
  # of the given Units declarations.
  #
  # @param [Array<Hash{Symbol => Array<:Symbol>}>] declarations the list of Unit declarations.
  #
  # @example
  #  declarations = [{uses: [:attribute1, ...], provides: [:result], ...}]
  #  attributes = Sequencer::Units::Attributes(declarations)
  class Attributes < Delegator

    # Lists all `provides` declarations of the Units the instance was initialized with.
    #
    # @example
    #  attributes.provided
    #  # => [:result, ...]
    #
    # @return [Array<Symbol>] the list of all `provides` declarations
    def provided
      select do |_attribute, instance|
        instance.will_be_provided?
      end.keys
    end

    # Lists all `uses` declarations of the Units the instance was initialized with.
    #
    # @example
    #  attributes.used
    #  # => [:attribute1, ...]
    #
    # @return [Array<Symbol>] the list of all `uses` declarations
    def used
      select do |_attribute, instance|
        instance.will_be_used?
      end.keys
    end

    # Checks if the given attribute is known in the list of Unit declarations.
    #
    # @example
    #  attributes.known?(:attribute2)
    #  # => false
    #
    # @return [Boolean]
    def known?(attribute)
      key?(attribute)
    end

    def __getobj__
      @attributes
    end

    def __setobj__(declarations)
      @attributes ||= begin # rubocop:disable Naming/MemoizedInstanceVariableName
        attributes = Hash.new do |hash, key|
          hash[key] = Sequencer::Units::Attribute.new
        end

        attributes.tap do |result|

          declarations.each_with_index do |unit, index|

            unit[:uses].try(:each) do |attribute|
              result[attribute].to = index
            end

            unit[:provides].try(:each) do |attribute|
              next if result[attribute].will_be_provided?

              result[attribute].from = index
            end

            unit[:optional].try(:each) do |attribute|
              result[attribute].optional = index
            end
          end
        end
      end
    end
  end
end